For the HTTP task, the default parallel setting is smooth, but you can change it to fastest, it could increase your download speed and save your time about 1-30 seconds.
But changing it to the fastest may cause your IP address to be blocked by the remote server. (low probability)
For the Torrent task, you can add trackers to increase your download & upload speed. But the condition is other peers are using the same tracker and downloading or uploading the same file.